Golf club head

ABSTRACT

A head  2  includes a head body h 1  and at least one weight . The head body h 1  includes a face  10 , an upper-side weight-disposal part Wa positioned on an upper side of a center of gravity HG of the head body h 1 , and a lower-side weight-disposal part Wb positioned on a lower side of the center of gravity HG of the head body h 1 . At least one of the upper-side weight-disposal part Wa and the lower-side weight-disposal part Wb is configured to change mass distribution in a toe-heel direction. The upper-side weight-disposal part Wa may be constituted of a first weight port WP 1  and a second weight port WP 2 . The lower-side weight-disposal part Wb may be constituted of a third weight port WP 3  and a fourth weight port WP 4.

The present application claims priority on Patent Application No.2015-61180 filed in JAPAN on Mar. 24, 2015, the entire contents of whichare hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a golf club head.

2. Description of the Related Art

A golf club having excellent flight distance performance has beendesired. As means for improving the flight distance performance, therehave been known the increase in the coefficient of restitution of aface, the increase in the mass of a head, the increase in the length ofa club, and the adjustment of the position of the center of gravity ofthe head, or the like (see the following Patent Literatures 1 to 3).

Meanwhile, the increase in an average flight distance has been attemptedin consideration of the variation in golfer's hitting points (see thefollowing Patent Literature 4).

Patent Literature 1: U.S. Patent Application Publication No.2013/0109501

Patent Literature 2: U.S. Patent Application Publication No.2013/0324299

Patent Literature 3: U.S. Patent Application Publication No.2014/0106901

Patent Literature 4: Japanese Patent No. 3,063,967 (USP5,836,830)

SUMMARY OF THE INVENTION

There is a limit on the increase in the coefficient of restitution of aface due to the regulation of the rules . There is a limit on theincrease in the mass of a head and the increase in the length of a clubfrom the viewpoint of the easiness of swing. There is a limit on thefreedom degree of design of the center of gravity of the head from therestriction of the volume of the head or the like.

A principal axis of inertia is considered in Japanese Patent No.3,063,967. This is effective in the increase in an average flightdistance, and there is still potential for improvement. The presentinventor completed a new invention for mass distribution capable ofimproving the flight distance performance of a head.

It is an object of the present invention to provide a golf club headcapable of exhibiting excellent flight distance performance for eachgolfer.

A preferable golf club head includes a head body and at least oneweight. The head body includes a face, an upper-side weight-disposalpart positioned on an upper side of a center of gravity of the headbody, and a lower-side weight-disposal part positioned on a lower sideof the center of gravity of the head body. At least one of theupper-side weight-disposal part and the lower-side weight-disposal partis configured to change mass distribution in a toe-heel direction.

Preferably, the upper-side weight-disposal part is constituted of afirst weight port and a second weight port. Preferably, the lower-sideweight-disposal part is constituted of a third weight port and a fourthweight port.

The center of gravity of the head body is defined as an origin in a basestate where the head is disposed on a level surface at a predeterminedlie angle and loft angle; a straight line in the toe-heel directionpassing through the origin is defined as an x-axis; a straight line in avertical direction passing through the origin is defined as a y-axis;and a plane parallel to the x-axis and the y-axis is defined as an xyplane. Preferably, in the head, a specific xy plane satisfying all ofthe following (a) to (d) exists:

(a) a distance between the specific xy plane and the first weight portis equal to or less than 20 mm;

(b) a distance between the specific xy plane and the second weight portis equal to or less than 20 mm;

(c) a distance between the specific xy plane and the third weight portis equal to or less than 20 mm; and

(d) a distance between the specific xy plane and the fourth weight portis equal to or less than 20 mm.

An xy coordinate system is constituted of the x-axis and the y-axis inplanar view from a face side. Preferably, in the planar view, the firstweight port is positioned in a first quadrant of the xy coordinatesystem; the second weight port is positioned in a second quadrant of thexy coordinate system; the third weight port is positioned in a thirdquadrant of the xy coordinate system; and the fourth weight port ispositioned in a fourth quadrant of the xy coordinate system.

Of three principal axes of inertia orthogonal to each other, a principalaxis of inertia having the smallest angle with respect to the y-axis isprojected on the xy plane to obtain a straight line. The straight lineis defined as a base line, and the angle between the base line and they-axis is defined as an inclination of the principal axis of inertia.

A height of a center of gravity of the head is defined as Gy, and aposition of the center of gravity of the head in the toe-heel directionis defined as Gx. Preferably, the head is configured to change theinclination of the principal axis of inertia without changing the heightGy and the position Gx.

A height of a center of gravity of the head is defined as Gy and aposition of the center of gravity of the head in the toe-heel directionis defined as Gx. Preferably, the head is configured to change theposition Gx without changing the height Gy. Preferably, the head isconfigured to change the position Gy without changing the position Gx.

Preferably, an adjustable range of the height Gy is 1 mm or greater and10 mm or less under a condition where a mass of the head is constant.

Preferably, an adjustable range of the position Gx is 1 mm or greaterand 15 mm or less under a condition where a mass of the head isconstant.

Preferably, an adjustable range of the inclination of the principal axisof inertia is 1 degree or greater and 20 degrees or less under acondition where a mass of the head is constant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a golf club head according to a firstembodiment;

FIG. 2 is a top view of the head of FIG. 1, and two weight ports aresimplified in FIG. 2;

FIG. 3 is a bottom view of the head of FIG. 1, and weights are omittedin FIG. 3;

FIG. 4 is a front view showing the inside of the head of FIG. 1;

FIG. 5 is a perspective view of the head of FIG. 1 viewed from a soleside;

FIG. 6 is a top view of a head according to a second embodiment, and thepositions of two weight ports are represented by hatching in FIG. 6;

FIG. 7 is a bottom view of the head according to the second embodiment,and the positions of two weight ports are represented by hatching inFIG. 7;

FIG. 8 is a top view of a head according to a third embodiment;

FIG. 9 is a bottom view of the head according to a third embodiment, andthe positions of four weight ports are represented by hatching in FIG.9;

FIG. 10 is a side view of the head according to the third embodiment,and the position of one weight port is represented by hatching in FIG.10;

FIG. 11 is a top view of a head according to a fourth embodiment, andthe positions of two weight ports are represented by hatching in FIG.11;

FIG. 12 is a bottom view of the head according to the fourth embodiment;

FIG. 13 is a top view of a head according to a fifth embodiment, and theposition of one weight port is represented by hatching in FIG. 13;

FIG. 14 is a bottom view of the head according to the fifth embodiment;

FIG. 15 is a top view of a head according to a sixth embodiment, and thepositions of two weight ports are represented by hatching in FIG. 15;and

FIG. 16 is a bottom view of the head according to the sixth embodiment,and the positions of two weight ports are represented by hatching inFIG. 16.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described below in detail based onpreferred embodiments with appropriate reference to the drawings.

FIG. 1 is a front view of a golf club head 2 (head body h1) according toa first embodiment of the present invention. FIG. 2 is a top view of thehead 2. FIG. 3 is a bottom view of the head 2. In a sole of FIG. 3,members other than two weight ports are omitted. The sole of the head 2are shown in detail in FIG. 5 to be described later.

The head 2 is a wood type head. The head 2 is a so-called driver head.The head 2 may be a utility type (hybrid type) head. The head 2 may bean iron type head. The head 2 may be a putter type head.

The head 2 includes the head body h1 and a weight. The number of weightsmay be 1, or equal to or greater than 2. In FIG. 2, the weights aresimplified as a simple cylinder. The weights are omitted in FIG. 3.These weights will be described in detail later.

The head body h1 includes a crown 4, a sole 6, a hosel 8, and a face 10.The crown 4 extends toward the back side of the head from the upper edgeof the face 10. The sole 6 extends toward the back side of the head fromthe lower edge of the face 10. The outer surface of the face 10 is ahitting surface. The hitting surface is also referred to as a facesurface. As shown in FIG. 2, the hosel 8 has a hosel hole 12.

Furthermore, the head body h1 includes a side part 14. The side part 14extends between the crown 4 and the sole 6. The side part 14 is alsoreferred to as a skirt. The side part 14 may not exist.

The inside of the head body h1 is a space. In other words, the head bodyhl is hollow.

[Definitions of Terms]

The following terms are defined in the present application.

[Base State and Base Perpendicular Plane]

A base perpendicular plane perpendicular to a level surface H is set(abbreviated in the drawings). A state where a center axis line Z1 of ashaft hole of a head is included in the base perpendicular plane and thehead is placed at a specified lie angle and real loft angle on the levelsurface H is defined as abase state (abbreviated in the drawings). Thespecified lie angle and real loft angle are described in, for example, aproduct catalog.

[Toe-Heel Direction]

A toe-heel direction is a direction of an intersection line between thebase perpendicular plane and the level surface H.

[Face-Back Direction]

A face-back direction is a direction perpendicular to the toe-heeldirection and parallel to the level surface H.

[Vertical Direction]

A vertical direction is a direction perpendicular to the level surfaceH.

[Center of Gravity HG of Head Body]

A head body in the present application means a portion excluding adetachably attached weight. Therefore, the center of gravity HG of thehead body is a center of gravity in a state where all detachablyattached weight(s) are detached.

[Center of Gravity of Head]

The center of gravity of a head is a center of gravity in a state whereall detachably attached weight(s) are attached to the head. Therefore,the center of gravity of the head does not necessarily coincide with thecenter of gravity HG of the head body.

[X-Axis]

A straight line passing through the center of gravity HG of the headbody and being parallel to the toe-heel direction is defined as anx-axis. An x-coordinate is zero in the center of gravity HG, with a heelside as a plus and a toe side as a minus.

[Y-Axis]

A straight line passing through the center of gravity HG of the headbody and being parallel to the vertical direction is defined as ay-axis. A y coordinate is zero in the center of gravity HG, with anupper side as a plus and a lower side as a minus. The y-axis isperpendicular to the x-axis.

[Z-Axis]

A straight line passing through the center of gravity HG of the headbody and being parallel to the face-back direction is defined as az-axis. A z coordinate is zero in the center of gravity HG, with a backside as a plus and a face side as a minus. The z-axis is perpendicularto the x-axis and the y-axis.

[XY Plane]

A plane parallel to the x-axis and the y-axis is an xy plane . The zcoordinate of the xy plane is not limited. Innumerable xy planes exist.

[Specific XY Plane]

A specific xy plane is one xy plane selected from the innumerable xyplanes which may exist. The z coordinate of the specific xy plane is notlimited.

[Planar View]

A projection image projected on the xy plane from the face side isplanar view. The direction of the projection is a directionperpendicular to the xy plane. FIG. 4 shows an example of the planarview.

[XY Coordinate System]

A plane coordinate system obtained by projecting the x-axis and they-axis on the xy plane is an xy coordinate system. The direction of theprojection is a direction perpendicular to the xy plane.

FIG. 4 is a front view showing the inside of the head 2 (head body h1).In order to show the inside of the head 2, a part of the face 10 isremoved in FIG. 4. The head body h1 includes a first weight port WP1, asecond weight port WP2, a third weight port WP3, and a fourth weightport WP4. Other weight ports may be further provided.

A weight may be disposed in the weight port. The weight may bedetachably attached to the weight port. The weight may be detachablyattached to each of the weight ports WP1, WP2, WP3, and WP4.

The first weight port WP1 is provided in the crown 4. The second weightport WP2 is provided in the crown 4. The first weight port WP1 isprovided on a heel side with respect to the second weight port WP2. Thefirst weight port WP1 is provided on an upper side of the center ofgravity HG of the head body h1. The second weight port WP2 is providedon an upper side of the center of gravity HG. The first weight port WP1is provided on a heel side with respect to the center of gravity HG. Thesecond weight port WP2 is provided on a toe side with respect to thecenter of gravity HG.

The position of the first weight port WP1 in the x-axis direction isdifferent from the position of the second weight port WP2 in the x-axisdirection. In other words, the position of the first weight port WP1 inthe toe-heel direction is different from the position of the secondweight port WP2 in the toe-heel direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The position of the first weight port WP1 in the y-axis direction may bedifferent from the position of the second weight port WP2 in the y-axisdirection. In other words, the position of the first weight port WP1 inthe vertical direction may be different from the position of the secondweight port WP2 in the vertical direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The position of the first weight port WP1 in the z-axis direction may bedifferent from the position of the second weight port WP2 in the z-axisdirection. In other words, the position of the first weight port WP1 inthe face-back direction may be different from the position of the secondweight port WP2 in the face-back direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The third weight port WP3 is provided in the sole 6. The fourth weightport WP4 is provided in the sole 6. The fourth weight port WP4 isprovided on a heel side with respect to the third weight port WP3. Thethird weight port WP3 is provided on a lower side of the center ofgravity HG of the head body h1. The fourth weight port WP4 is providedon a lower side of the center of gravity HG. The third weight port WP3is provided on a toe side with respect to the center of gravity HG. Thefourth weight port WP4 is provided on a heel side with respect to thecenter of gravity HG.

The position of the third weight port WP3 in the x-axis direction isdifferent from the position of the fourth weight port WP4 in the x-axisdirection. In other words, the position of the third weight port WP3 inthe toe-heel direction is different from the position of the fourthweight port WP4 in the toe-heel direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The position of the third weight port WP3 in the y-axis direction may bedifferent from the position of the fourth weight port WP4 in the y-axisdirection. In other words, the position of the third weight port WP3 inthe vertical direction may be different from the position of the fourthweight port WP4 in the vertical direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The position of the third weight port WP3 in the z-axis direction may bedifferent from the position of the fourth weight port WP4 in the z-axisdirection. In other words, the position of the third weight port WP3 inthe face-back direction may be different from the position of the fourthweight port WP4 in the face-back direction. The position difference canimprove the freedom degree of the adjustment of the center of gravity ofthe head.

The first weight port WP1 is provided on a back side with respect to thecenter of gravity HG. The second weight port WP2 is provided on a backside with respect to the center of gravity HG. The third weight port WP3is provided on a back side with respect to the center of gravity HG. Thefourth weight port WP4 is provided on a back side with respect to thecenter of gravity HG.

The first weight port WP1 may be provided on a face side with respect tothe center of gravity HG. The second weight port WP2 maybe provided on aface side with respect to the center of gravity HG. The third weightport WP3 may be provided on a face side with respect to the center ofgravity HG. The fourth weight port WP4 may be provided on a face sidewith respect to the center of gravity HG.

The head body h1 includes an upper-side weight-disposal part Wapositioned on an upper side of the center of gravity HG of the head bodyh1. In the present embodiment, the upper-side weight-disposal part Wa isconstituted of the first weight port WP1 and the second weight port WP2.The upper-side weight-disposal part Wa is configured to change massdistribution in the toe-heel direction. By changing the massdistribution of the weight disposed in the first weight port WP1 and theweight disposed in the second weight port WP2, the mass distribution inthe toe-heel direction can be changed.

The head body h1 includes a lower-side weight-disposal part Wbpositioned on a lower side of the center of gravity HG of the head bodyh1. In the present embodiment, the lower-side weight-disposal part Wb isconstituted of the third weight port WP3 and the fourth weight port WP4.The lower-side weight-disposal part Wb is configured to change massdistribution in the toe-heel direction. By changing the massdistribution of the weight disposed in the third weight port WP3 and theweight disposed in the fourth weight port WP4, the mass distribution inthe toe-heel direction can be changed.

Thus, in the present embodiment, both the upper-side weight-disposalpart Wa and the lower-side weight-disposal part Wb allow mass transferin the toe-heel direction. Either the upper-side weight-disposal part Waor the lower-side weight-disposal part Wb may allow the mass transfer inthe toe-heel direction.

FIG. 4 is also planar view from the face side. All structures includedin the head body h1 (head 2) are assumed to be projected in the planarview. Therefore, the inside structure of the head 2 is also reflected inthe planar view. The xy coordinate system is constituted in the planarview. A two-dot chain line Lx in FIG. 4 is an x-axis of the xycoordinate system. A two-dot chain line Ly in FIG. 4 is a y-axis of thexy coordinate system.

As shown in FIG. 4, the first weight port WP1 is positioned in a firstquadrant Q1 of the xy coordinate system. The second weight port WP2 ispositioned in a second quadrant Q2 of the xy coordinate system. Thethird weight port WP3 is positioned in a third quadrant Q3 of the xycoordinate system. The fourth weight port WP4 is positioned in a fourthquadrant Q4 of the xy coordinate system.

Thus, the first to fourth weight ports are respectively distributed tothe first quadrant Q1, the second quadrant Q2, the third quadrant Q3,and the fourth quadrant Q4. By the distribution, the adjustment of thecenter of gravity of the head can be realized with a high freedomdegree. By the distribution, the adjustment of the inclination of aprincipal axis of inertia can be realized with a high freedom degree.

A recess in which the weight is disposed is usually provided in theweight port. The position of the weight port can be assumed to be theposition of the center of gravity of a substance having a constantspecific gravity when the recess formed in the weight port is filledwith the substance. The position of the center of gravity of the filledsubstance is usually substantially equal to the position of the centerof gravity of the weight mounted in the weight port. For example, theposition of the weight port can be assumed to be the position of thecenter of gravity of the weight when a stainless steel weight of 4 g isattached to the weight port.

As shown in FIG. 2, a specific xy plane SP1 satisfying all of thefollowing (a) to (d) exists in the head 2. In FIG. 2, the specific xyplane SP1 is represented by one straight line (two-dot chain line):

(a) a distance between the specific xy plane SP1 and the first weightport WP1 is equal to or less than 20 mm;

(b) a distance between the specific xy plane SP1 and the second weightport WP2 is equal to or less than 20 mm;

(c) a distance between the specific xy plane SP1 and the third weightport WP3 is equal to or less than 20 mm; and

(d) a distance between the specific xy plane SP1 and the fourth weightport WP4 is equal to or less than 20 mm.

In the head 2 satisfying the above (a) to (d), the positions of the fourweight ports in the face-back direction are close to each other.Therefore, the mass distribution can be changed while the movement ofthe center of gravity of the head in the face-back direction issuppressed. For example, the position of a sweet spot can be changedwhile the variation in the depth of the center of gravity is suppressed.For example, the inclination of the principal axis of inertia can bechanged without substantially moving the position of the center ofgravity of the head in the face-back direction.

In the present embodiment, a number of specific xy planes SP1 exist. Thespecific xy plane SP1 is selected from a number of xy planes. In FIG. 2,a plane SP11 and a plane SP12 are shown as the specific xy plane SP1,but these are two examples of a number of specific xy planes SP1.

From the above-mentioned viewpoint, a specific xy plane SP1 satisfyingall of the following (a1) to (d1) more preferably exists:

(a1) a distance between the specific xy plane SP1 and the first weightport WP1 is equal to or less than 15 mm;

(b1) a distance between the specific xy plane SP1 and the second weightport WP2 is equal to or less than 15 mm;

(c1) a distance between the specific xy plane SP1 and the third weightport WP3 is equal to or less than 15 mm; and

(d1) a distance between the specific xy plane SP1 and the fourth weightport WP4 is equal to or less than 15 mm.

From the above-mentioned viewpoint, a specific xy plane SP1 satisfyingall of the following (a2) to (d2) more preferably exists:

(a2) a distance between the specific xy plane SP1 and the first weightport WP1 is equal to or less than 10 mm;

(b2) a distance between the specific xy plane SP1 and the second weightport WP2 is equal to or less than 10 mm;

(c2) a distance between the specific xy plane SP1 and the third weightport WP3 is equal to or less than 10 mm; and

(d2) a distance between the specific xy plane SP1 and the fourth weightport WP4 is equal to or less than 10 mm.

The specific xy plane SP12 (see FIG. 2) satisfies all of the following(a3) to (d3):

(a3) a distance between the specific xy plane SP12 and the first weightport WP1 is equal to or less than 3 mm;

(b3) a distance between the specific xy plane SP12 and the second weightport WP2 is equal to or less than 3 mm;

(c3) a distance between the specific xy plane SP12 and the third weightport WP3 is equal to or less than 3 mm; and

(d3) a distance between the specific xy plane SP12 and the fourth weightport WP4 is equal to or less than 3 mm.

In the present application, the height of the center of gravity of thehead is defined as Gy. The height Gy can be specified by the ycoordinate of the center of gravity of the head. In the presentapplication, the position of the center of gravity of the head in thetoe-heel direction is defined as Gx. The position Gx can be specified bythe x-coordinate of the center of gravity of the head.

The head 2 is configured to change the position Gx without changing theheight Gy. The position Gx can be changed without (substantially)changing the height Gy by changing the mass distribution of the weightsdisposed in the four weight ports. Therefore, the freedom degree of theadjustment is improved. For example, each golfer can easily adjust thesweet spot according to the position of the golfer's hitting point. Thephrase “without changing the height Gy” means that the change of theheight Gy is equal to or less than 1.0 mm.

The head 2 is configured to change the height Gy without changing theposition Gx. The height Gy can be changed without (substantially)changing the position Gx by changing the mass distribution of theweights disposed in the four weight ports. Therefore, the freedom degreeof the adjustment is improved. For example, each golfer can easilyadjust the sweet spot according to the position of the golfer's hittingpoint. The phrase “without changing the position Gx” means that thechange of the position Gx is equal to or less than 1.0 mm.

In the present application, the principal axis of inertia of the head isconsidered. All objects have been known to have three principal axes ofinertia orthogonal to each other. The head 2 also has three principalaxes of inertia orthogonal to each other. Due to the mass and positionof the weight, the mass distribution of the head 2 is changed, and thedirection of the principal axis of inertia is also changed.

Of three principal axes of inertia orthogonal to each other, a principalaxis of inertia having the smallest angle with respect to the y-axis isprojected on the xy plane to obtain a straight line. The straight lineis defined as a base line, and the angle between the base line and they-axis is defined as an inclination of the principal axis of inertia.The angle is an angle in the planar view.

In the head 2, the inclination of the principal axis of inertia can bechanged without (substantially) changing the height Gy and the positionGx. Therefore, the freedom degree of the adjustment is improved. Forexample, each golfer can easily adjust the inclination of the principalaxis of inertia according to the distribution of the golfer's hittingpoints. The phrase “without changing the height Gy and the position Gx”means that the change of the height Gy is equal to or less than 1.0 mm,and the change of the position Gx is equal to or less than 1.0 mm.

Preferably, under a condition where the mass of the head is constant,the adjustable range of the height Gy is 1 mm or greater and 10 mm orless. The adjustable range of 1 mm or greater improves an effect by theheight Gy. Since the weight is heavy when the adjustable range isgreater than 10 mm, the mass of the head may be excessive. From theviewpoint of obtaining such a preferable adjustable range, a pluralityof weights are preferably used. From the viewpoint of the freedom degreeof the adjustment, the plurality of weights may include weights havingmasses different from each other.

Preferably, under a condition where the mass of the head is constant,the adjustable range of the position Gx are 1 mm or greater and 15 mm orless. The adjustable range of 1 mm or greater improves an effect by theposition Gx. Since the weight is heavy when the adjustable range isgreater than 15 mm, the mass of the head may be excessive. From theviewpoint of obtaining such a preferable adjustable range, a pluralityof weights are preferably used. From the viewpoint of the freedom degreeof the adjustment, the plurality of weights preferably include weightshaving masses different from each other.

Preferably, under a condition where the mass of the head is constant,the adjustable range of the inclination of the principal axis of inertiais 1 degree or greater and 20 degrees or less. The adjustable range of 1mm or greater improves an effect due to the inclination of the principalaxis of inertia. Since the weight is heavy when the adjustable range isgreater than 20 degrees, the mass of the head may be excessive. From theviewpoint of obtaining such a preferable adjustable range, a pluralityof weights are preferably used. From the viewpoint of the freedom degreeof the adjustment, the plurality of weights preferably include weightshaving masses different from each other.

[Weight]

The head 2 includes at least one weight. The number of the weights maybe 1. When one weight is moved to a plurality of positions, the massdistribution in the head 2 is largely changed. When one weight is movedto a plurality of positions, the center of gravity of the head can belargely moved.

A preferable weight is detachably attached to the first weight port WP1,and is detachably attached to the second weight port WP2. A preferableweight is detachably attached to the third weight port WP3, and isdetachably attached to the fourth weight port WP4. A more preferableweight is detachably attached to all of the first weight port WP1, thesecond weight port WP2, the third weight port WP3, and the fourth weightport WP4.

The head 2 may have a plurality of weights. The number of the weightsmay be 2, 3, 4, 5 or greater. The plurality of weights may have massesdifferent from each other. It is preferable that each of the pluralityof weights can be detachably attached to all of the first weight portWP1, the second weight port WP2, the third weight port WP3, and thefourth weight port WP4.

FIG. 5 is a perspective view of the head 2 viewed from a sole side. Aweight attaching/detaching mechanism M1 is provided in the third weightport WP3. The weight attaching/detaching mechanism M1 satisfies the GolfRules defined by Royal and Ancient Golf Club of Saint Andrews (R&A).That is, the weight attaching/detaching mechanism satisfies requirementsspecified in “1b Adjustability” in “1 Club” of “Appendix II Design ofClubs” defined by R&A. The requirements defined by the “1bAdjustability” are the following items (i), (ii), and (iii):

(i) the adjustment cannot be readily made;

(ii) all adjustable parts are firmly fixed and there is no reasonablelikelihood of them working loose during a round; and

(iii) all configurations of adjustment conform with the Rules.

The above-mentioned weight attaching/detaching mechanism M1 is providedalso in the fourth weight port WP4.

FIG. 5 includes an exploded perspective view of the weightattaching/detaching mechanism M1. One of the two weightattaching/detaching mechanisms M1 is shown in the exploded perspectiveview. As shown in the exploded perspective view, the weightattaching/detaching mechanism M1 includes a socket 20 and a weight 22.The first weight attaching/detaching mechanism M1 is fixed to the thirdweight port WP3. A recess is formed in the third weight port WP3. Thefirst socket 20 is accommodated in the recess. The second weightattaching/detaching mechanism M1 is fixed to the fourth weight port WP4.A recess is formed in the fourth weight port WP4. The second socket 20is accommodated in the recess.

The socket 20 includes a body part 20 a and a bottom forming part 20 b.The body part 20 a has a hole 24. The hole 24 passes through the bodypart 20 a. The socket 20 is fixed to the recess with an adhesive.

When the weight 22 is inserted into the hole 24, and the weight 22 isrotated at a predetermined angle θ, the weight 22 is fixed to the socket20. Even when the weight 22 is subjected to the shock of the hit ball,the fixation of the weight 22 is maintained. When the weight 22 isinversely rotated at an angle θ, the weight 22 is detached from thesocket 20. The weight 22 can be rotated by a torque wrench. The socket20 is configured so that the weight 22 can be attached and detached asdescribed above.

The weight attaching/detaching mechanism M1 is an attachment typeattaching/detaching mechanism. As described above, in the weightattaching/detaching mechanism M1, the weight can be attached by therotation of the angle θ, and the weight can be detached by the inverserotate of the angle θ. In the weight attaching/detaching mechanism M1,the weight is easily attached and detached. Such a weightattaching/detaching mechanism M1 is known. The weightattaching/detaching mechanism M1 is adopted for “SRIXON Z925 driver”(trade name) manufactured by Dunlop Sports Co., Ltd. or the like.

Thus, the weight 22 can be detachably attached to the socket 20.Therefore, the weight 22 is detachably attached to the third weight portWP3. Similarly, the weight 22 is detachably attached to the fourthweight port WP4.

Although not shown in the drawings, the weight attaching/detachingmechanism M1 may be applied also to each of the first weight port WP1and the second weight port WP2.

The weight attaching/detaching mechanism is not limited to theabove-mentioned mechanism M1. Another examples of the weightattaching/detaching mechanism include a screw type mechanism.

FIG. 6 is a top view of a head 30 according to a second embodiment, andFIG. 7 is a bottom view of the head 30. Except for the disposals of afirst weight port WP1, second weight port WP2, third weight port WP3,and fourth weight port WP4, the head 30 is the same as theabove-mentioned head 2. In FIGS. 6 and 7, each of the weight ports issimplistically represented by hatching.

The first weight port WP1 is provided on a face side with respect to thecenter of gravity HG. The second weight port WP2 is provided on a faceside with respect to the center of gravity HG. The third weight port WP3is provided on a face side with respect to the center of gravity HG. Thefourth weight port WP4 is provided on a face side with respect to thecenter of gravity HG. The positions of these weight ports contribute tobring a center of gravity of the head near the face. The center ofgravity of the head near the face is useful to lower a sweet spot.

FIG. 8 is a top view of a head 40 according to a third embodiment, andFIG. 9 is a bottom view of the head 40. FIG. 10 is a side view of thehead 40 viewed from a toe side. Except for the disposals of a firstweight port WP1, second weight port WP2, third weight port WP3, andfourth weight port WP4, the head 40 is the same as the above-mentionedhead 2. In FIGS. 9 and 10, each of the weight ports is simplisticallyrepresented by hatching.

As shown in FIG. 9, the first weight port WP1 is provided in a side part14. The first weight port WP1 is provided in the upper part of the sidepart 14 . Similarly, the second weight port WP2 is provided in the sidepart 14. As shown in FIGS. 9 and 10, the second weight port WP2 isprovided in the upper part of the side part 14. The third weight portWP3 and the fourth weight port WP4 are provided in a sole 6.

Thus, in the head 40, an upper-side weight-disposal part

Wa is provided in the side part. A lower-side weight-disposal part Wb isprovided in a sole part. As shown in FIG. 8, in the head 40, the weightport is not visually recognized at address. In the head 40, theupper-side weight-disposal part is not visually recognized at address.

FIG. 11 is a top view of a head 50 according to a fourth embodiment, andFIG. 12 is a bottom view of the head 50. In FIG. 11, each of the weightports is simplistically represented by hatching.

In the head 50, a first weight port WP1 and a second weight port WP2 areprovided in a crown 4. An upper-side weight-disposal part Wa isconstituted of the first weight port WP1 and the second weight port WP2as in the above-mentioned head 2. Meanwhile, in the head 50, alower-side weight-disposal part Wb is a weight slide mechanism. As shownin FIG. 12, the weight slide mechanism has a weight wl, a slide groovev1, and a screw t1. A slit s1 is formed in a bottom face of the slidegroove v1. The slide groove v1 extends substantially along a toe-heeldirection. The screw t1 passes through the weight w1 and the slit s1,and is screw-connected to a nut member (not shown). The nut member isdisposed inside a head body h1, and has such a size that the nut memberdoes not pass through the slit s1.

The weight w1 can be slid in the slide groove v1. By tightening thescrew tl, the weight w1 can be fixed at an optional position in theslide groove v1. By the movement of the weight w1, mass distribution inthe toe-heel direction can be changed. Thus, the lower-sideweight-disposal part Wb may be a weight slide mechanism. Similarly, theupper-side weight-disposal part Wa may be a weight slide mechanism. Theupper-side weight-disposal part Wa may be a weight slide mechanism, andthe weight slide mechanism may be provided in a side part 14.

FIG. 13 is a top view of a head 60 according to a fifth embodiment, andFIG. 14 is a bottom view of the head 60. In FIG. 13, a weight port issimplistically represented by hatching.

In the head 60, a first weight port WP1 is provided in a crown 4. Unlikethe above-mentioned head 50, a second weight port WP2 is not provided inthe head 60. The same weight slide mechanism as the weight slidemechanism of the head 50 is provided in a sole 6 of the head 60.

In the head 60, an upper-side weight-disposal part Wa is constituted ofonly the first weight port WP1. The upper-side weight-disposal part Wais not configured to change mass distribution in a toe-heel direction.Meanwhile, a lower-side weight-disposal part Wb is the above-mentionedweight slide mechanism. The lower-side weight-disposal part Wb isconfigured to change mass distribution in the toe-heel direction.

FIG. 15 is a top view of a head 70 according to a sixth embodiment, andFIG. 16 is a bottom view of the head 70. Except for the disposals of afirst weight port WP1, second weight port WP2, third weight port WP3,and fourth weight port WP4, the head 70 is the same as theabove-mentioned head 2. In FIGS. 15 and 16, each of the weight ports issimplistically represented by hatching.

As shown in FIG. 15, the first weight port WP1 is provided on a faceside with respect to a center of gravity HG of a head body h1.Similarly, the second weight port WP2 is provided on a face side withrespect to the center of gravity HG. Meanwhile, as shown in FIG. 16, thethird weight port WP3 is provided on a back side with respect to thecenter of gravity HG. Similarly, the fourth weight port WP4 is providedon a back side with respect to the center of gravity HG. The positionsof these weight ports contribute to the adjustment of the position ofthe center of gravity of the head in a face-back direction.

The specific xy plane SP1 exists also in the head 70. As describedabove, the specific xy plane SP1 satisfies all of the following (a) to(d) .

(a) a distance between the specific xy plane SP1 and the first weightport WP1 is equal to or less than 20 mm;

(b) a distance between the specific xy plane SP1 and the second weightport WP2 is equal to or less than 20 mm;

(c) a distance between the specific xy plane SP1 and the third weightport WP3 is equal to or less than 20 mm; and

(d) a distance between the specific xy plane SP1 and the fourth weightport WP4 is equal to or less than 20 mm.

The material of the head body h1 is not limited. Examples of thematerial of the head body h1 include a metal and CFRP (carbon fiberreinforced plastic). Examples of the metal include one or more kindsselected from soft iron, pure titanium, a titanium alloy, stainlesssteel, maraging steel, an aluminium alloy, a magnesium alloy, and atungsten-nickel alloy. Examples of the stainless steel include SUS630and SUS304. Examples of the titanium alloy include 6-4 titanium(Ti-6Al-4V) , Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S. The soft iron meanslow carbon steel having a carbon content of less than 0.3 wt %.

The material of the weight is not limited. Examples of the material ofthe weight include a metal. Examples of the metal include one or morekinds selected from soft iron, pure titanium, a titanium alloy,stainless steel, maraging steel, an aluminium alloy, a magnesium alloy,a tungsten-nickel alloy, and tungsten. Examples of the stainless steelinclude SUS630 and SUS304. Examples of the titanium alloy include 6-4titanium (Ti-6Al -4V), Ti-15V-3Cr-3Sn-3Al, and Ti-6-22-22S.

A preferable example of the head is a driver head. The driver means anumber 1 wood (W#1). High flight distance performance is required forthe driver. Therefore, the present invention is preferably applied.Usually, the driver head has the following constitution:

(1a) curved face surface;

(1b) hollow part;

(1c) volume of 300 cc or greater and 460 cc or less; and

(1d) real loft of 7 degrees or greater and 14 degrees or less.

Another preferable example of the head is a fairway wood head. Examplesof the fairway wood include a number 3 wood (W#3) , a number 4 wood(W#4), a number 5 wood (W#5), a number 7 wood (W#7), a number 9 wood(W#9), a number 11 wood (W#11), and a number 13 wood (W#13). Usually,the fairway wood head has the following constitution:

(2a) curved face surface;

(2b) hollow part;

(2c) volume of 100 cc or greater and less than 300 cc; and

(2d) real loft of greater than 14 degrees and 33 degrees or less.

More preferably, the volume of the fairway wood head is 100 cc orgreater and 200 cc or less.

Still another preferable example of the head is a utility type head(hybrid type head). Usually, the utility type head (hybrid type head)has the following constitution:

(3a) curved face surface;

(3b) hollow part;

(3c) volume of 100 cc or greater and 200 cc or less; and

(3d) real loft of 15 degrees or greater and 33 degrees or less.

More preferably, the volume of the utility type head (hybrid type head)is 100 cc or greater and 150 cc or less.

The present invention can be preferably used also for an iron head and aputter head.

EXAMPLES

Hereinafter, the effects of the present invention will be clarified byExamples. However, the present invention should not be interpreted in alimited way based on the description of Examples.

[Production of Head Body]

Three-dimensional data having the same shape as the shape of theabove-mentioned head body hl was produced. The shape of the head body h1was made the same as the shape of “SRIXON Z925 driver (trade name): loft9.5 degrees” manufactured by Dunlop Sports Co., Ltd. Four weight portsWP1, WP2, WP3, and WP4 were set as in the above-mentioned head 2. Thepositions of the third weight port WP3 and fourth weight port WP4 weremade the same as the positions of weight ports provided in “SRIXON Z925driver”.

The following Table 1 shows the position of the center of gravity of theweight disposed in each weight port. Disposal A represents thecoordinate of the center of gravity of a weight of 8 g when the weightis disposed in only the second weight port WP2. Disposal B representsthe coordinate of the center of gravity of a weight of 8 g when theweight is disposed in only the first weight port WP1. Disposal Crepresents the coordinate of the center of gravity of a weight of 8 gwhen the weight is disposed in only the third weight port WP3. DisposalD represents the coordinate of the center of gravity of a weight of 8 gwhen the weight is disposed in only the fourth weight port WP4.

As represented by these coordinates, the first weight port WP1 is in thefirst quadrant Q1 in planar view; the second weight port WP2 is in thesecond quadrant Q2 in planar view; the third weight port WP3 is in thethird quadrant Q3 in planar view; and the fourth weight port WP4 is inthe fourth quadrant Q4 in planar view. The coordinates shown in Table 1are values when the position of the center of gravity of referenceexample is defined as an origin. The reference example is a head towhich a weight is not attached. The center of gravity of the referenceexample is a center of gravity HG of the head body h1.

For example, when a specific xy plane SP1 was set at a position of whicha z coordinate was 29.0, all the distances between the specific xy planeSP1 and each of the coordinates were less than 10 mm (furthermore, lessthan 3 mm).

Example 1

The head body was equipped with four weights. The masses of theseweights were 4 g. Weights were disposed in all of the four weight ports.The position of the center of gravity of the head of Example 1 wascalculated. Furthermore, the inclination of a principal axis of inertiawas calculated. The results are shown in the following Table 2. The signof the inclination of the principal axis of inertia is equal to the signof the inclination of the base line with respect to the y-axis in an xycoordinate system, and clockwise rotation is positive.

Example 2

Two weights were used in Example 2. The masses of these weights were 8g. The weights were disposed in a second weight port WP2 and a thirdweight port WP3. In the same manner as in Example 1 as for the rest, theposition of a center of gravity and the inclination of a principal axisof inertia of a head of Example 2 were obtained. As the position of thecenter of gravity of the head, the relative position of the center ofgravity of Example 2 with respect to the reference example having noweight and the relative position of the center of gravity of Example 2with respect to Example 1 were calculated. These results are shown inthe following Table 2.

Examples 3 to 7

Two weights were used also in Examples 3 to 7. The positions of thecenters of gravity (two kinds) and the inclinations of principal axes ofinertia of heads of Examples 3 to 7 were calculated in the same manneras in Example 2 except that the disposals of the weights were as shownin Table 2. These results are shown in the following Table 2.

TABLE 1 Position of weight disposed in each weight port Reference Weightexample Disposal Disposal Disposal Disposal port (head body) A B C DDisposal of Toe side of WP2 0 8 0 0 0 single crown weight (g) Heel sideWP1 0 0 8 0 0 of crown Toe side of WP3 0 0 0 8 0 sole Heel side WP4 0 00 0 8 of sole Relative x (mm) — 0.0 −31.3 20.6 −35.2 24.8 position of y(mm) — 0.0 26.8 18.6 −4.8 −8.6 center of z (mm) — 0.0 29.7 26.0 31.327.9 gravity of weight (with respect to no weight)

TABLE 2 Specifications and evaluation results of Examples Weight ExampleExample Example Example Example Example Example port 1 2 3 4 5 6 7Disposal of Toe side of WP2 4 8 0 8 0 8 0 weight (g) crown Heel side WP14 0 8 8 0 0 8 of crown Toe side of WP3 4 8 0 0 8 0 8 sole Heel side WP44 0 8 0 8 8 0 of sole Relative x (mm) — −0.4 −2.7 1.8 −0.4 −0.4 −0.3−0.6 position of y (mm) — 0.7 0.9 0.4 1.8 −0.5 0.7 0.6 center of z (mm)— 2.3 2.5 2.2 2.3 2.4 2.3 2.3 gravity (with respect to no weight)Relative x (mm) — 0.0 −2.3 2.3 0.0 0.0 0.2 −0.2 position of y (mm) — 0.00.2 −0.2 1.2 −1.2 0.1 −0.1 center of z (mm) — 0.0 0.1 −0.1 −0.1 0.1 0.00.0 gravity (with respect to Example 1) Inclination of principal — −2.4−0.9 −4.1 −3.1 −1.9 0.7 −5.3 axis of inertia (degree)

Examples 1 to 7 had the same head mass. In Examples 2 to 7, two weightswere used, and the freedom degree of the position of the center ofgravity was high. In comparison of Example 2 with Example 3, anx-coordinate was changed by 4 mm or greater while the changes of y and zcoordinates were suppressed to 0.4 mm or less. That is, the amount ofchange of the x-coordinate was equal to or greater than 10 times basedon the amounts of change of the y and z coordinates. In comparison ofExample 4 with Example 5, a y-coordinate was changed by 2 mm or greaterwhile the changes of x and z coordinates were suppressed to 0.1 mm orless. That is, the amount of change of the y-coordinate was equal to orgreater than 20 times based on the amounts of change of the x and zcoordinates. In comparison of Example 6 with Example 7, the inclinationof a principal axis of inertia was changed by 5 mm or greater while thechanges of x, y and z coordinates were suppressed to 0.2 mm or less.Thus, the adjustment of the center of gravity of the head was achievedwith a high freedom degree. The freedom degree allows adjustmentcomplying with each golfer. The freedom degree facilitates customfitting.

The present invention can be applied to all golf club heads such as awood type, utility type, hybrid type, iron type, and putter type golfclub heads.

The above description is only illustrative and various changes can bemade without departing from the scope of the present invention.

What is claimed is:
 1. A golf club head comprising: a head body; and atleast one weight, wherein: the head body includes an upper-sideweight-disposal part positioned on an upper side of a center of gravityof the head body, and a lower-side weight-disposal part positioned on alower side of the center of gravity of the head body; and at least oneof the upper-side weight-disposal part and the lower-sideweight-disposal part is configured to change mass distribution in atoe-heel direction.
 2. The golf club head according to claim 1, wherein:the upper-side weight-disposal part is constituted of a first weightport and a second weight port; and the lower-side weight-disposal partis constituted of a third weight port and a fourth weight port.
 3. Thegolf club head according to claim 2, wherein if the center of gravity ofthe head body is defined as an origin in a base state where the head isdisposed on a level surface at a predetermined lie angle and loft angle;a straight line in the toe-heel direction passing through the origin isdefined as an x-axis; a straight line in a vertical direction passingthrough the origin is defined as a y-axis; and a plane parallel to thex-axis and the y-axis is defined as an xy plane, a specific xy planesatisfying all of the following (a) to (d) exists: (a) a distancebetween the specific xy plane and the first weight port is equal to orless than 20 mm; (b) a distance between the specific xy plane and thesecond weight port is equal to or less than 20 mm; (c) a distancebetween the specific xy plane and the third weight port is equal to orless than 20 mm; and (d) a distance between the specific xy plane andthe fourth weight port is equal to or less than 20 mm.
 4. The golf clubhead according to claim 3, wherein: an xy coordinate system isconstituted of the x-axis and the y-axis in planar view from a faceside; and in the planar view, the first weight port is positioned in afirst quadrant of the xy coordinate system; the second weight port ispositioned in a second quadrant of the xy coordinate system; the thirdweight port is positioned in a third quadrant of the xy coordinatesystem; and the fourth weight port is positioned in a fourth quadrant ofthe xy coordinate system.
 5. The golf club head according to claim 3,wherein: the golf club head includes three principal axes of inertiaorthogonal to each other; and of the three principal axes of inertia, aprincipal axis of inertia having the smallest angle with respect to they-axis is projected on the xy plane to obtain a straight line, thestraight line is defined as a base line, and the angle between the baseline and the y-axis is defined as an inclination of the principal axisof inertia; a height of a center of gravity of the head is defined asGy; and a position of the center of gravity of the head in the toe-heeldirection is defined as Gx, the head is configured to change theinclination of the principal axis of inertia without changing the heightGy and the position Gx.
 6. The golf club head according to claim 1,wherein if a height of a center of gravity of the head is defined as Gyand a position of the center of gravity of the head in the toe-heeldirection is defined as Gx, the head is configured to change theposition Gx without changing the height Gy, and the head is configuredto change the position Gy without changing the position Gx.
 7. The golfclub head according to claim 5, wherein an adjustable range of theheight Gy is 1 mm or greater and 10 mm or less under a condition whereamass of the head is constant.
 8. The golf club head according to claim5, wherein an adjustable range of the position Gx is 1 mm or greater and15 mm or less under a condition where a mass of the head is constant. 9.The golf club head according to claim 1, wherein: the golf club headincludes three principal axes of inertia orthogonal to each other; andof the three principal axes of inertia, a principal axis of inertiahaving the smallest angle with respect to the y-axis is projected on thexy plane to obtain a straight line, the straight line is defined as abase line, and the angle between the base line and the y-axis is definedas an inclination of the principal axis of inertia, an adjustable rangeof the inclination of the principal axis of inertia is 1 degree orgreater and 20 degrees or less under a condition where a mass of thehead is constant.